Telephone device



Feb. 2s, 192s. 1,660,864

\ F. CONRAD TELEPHONE DEVI GE Filed Jan. 5. v1923 any VII

, )N C I 00L/b e /000 d A n c Jm/e WITNEssEs; 00 VmvENToR Fran/f Conrad /oa man /oooo BY one embodiment of my invention,the sec-A tion being taken on the lines I-I of Figs.

Patented Feb. as, 1928.

UNITED STATESl 1,660,864 PATENT@ oFFica.

FRANK CONRAD, 0F PITTSBURGH, PIENNSYLV'AN'IA',` ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

TELEPHONE DEYICE.

Applicatiox led January 5, 1:9281k Serial No. 610,7-75.

My invention relates to telephone apparatus having particular relation to sound-- wave translating devices.

The principal object of my invention is to.

provide apparatus of the` class described,

wherein substantially the same intensity of response is obtained for all signal currents within the audible range, and wherein an extremely high degree of sensitivity is obtained in the translation of the signal currents into sound waves, and vice versa.

` I have found that, in the ordinary telephone construction, the intensity of the permanent magnetic iux is such as to cause saturation of the diaphragm, thereby greatly decreasing the flux variations produced by the signal currents.

According to my invention, I provide a telephone construction which obviatesthe aforementioned difficulties by directing the unidirectional flux of the permanent magnet throughs the diaphragm transversely to the plane thereof. The telephone construction comprises a magnetizable member having pole pieces, asecond magnetizablemember; `havings'imilar pole pieces, the pole pieces of one magnetizable member being so disposed as to face, in spaced relation, the pole pieces, of opposite sign, of the other magnetiable member, a magnetizable diaphragm vibratably positioned in the space intermediate said pole pieces, andsignal current windings carried by said pole pieces.

With these and other objects in view, my

invention further consists in the details of construction and in the operation and circuit arrangement set forth in the following description and claims and illustrated in the accompanying drawing, wherein,

Figure 1 is a horizontal sectional view of applied to a telephone transmitter, and

Fig. 6 is a curve diagram illustrating one advantage of my construction over that of the ordinary telephone device.

In Figs. 1, 2 and 4, is shown a particular embodiment of my invention, which has ing 9 may carry binding. 1

proved satisfactory, comprising a pair of telephone receivers 1 and 2, of the magnetic t pe, having a common vibratory diaphragm e ement 3. l

The receiver 1 comprises a pair of softiron pole pieces 4 and 5 carrying magnetizlng windings 6 and 7 respectively, said po e pieces serving as pole terminals 'for a permanent magnet 8. The several foreg'on elements may be embodied in a casing 9 o non-magnetizable material, and securedin any wellknown manner therein. The casposts 11 and 12 :for the magnetizing win ngs-6 and 7.

The receiver 2 is similar to the receiver 1 and comprises va corresponding pair of soft-iron pole ieces 18 and 14 carrying magnetizable win ings l5 andA 16, respectivel said pole pieces serving as pol termina S for a permanent magnet 17. The severalelements may be supported in a casing y18 in any well known manner. vrI he casing 18 may be provided with a perforation 19 for reasons which will appear hereinafter. Binding posts 22" and 22', which are carried by `the receiver casing 18, serve as external connectors for the magnetizing windings 15 and 16. p i

The telephone receivers l and 2 may be brought together to form a completed structure, as shown in Fig. 1, by means of a cylindrical outer casing 21 of such dimensions as to removably recelve the telephone receivers l and 2 from an open end 23. The opposite end of the casing is provided with perforations 24 and 25 for receiving the binding posts 22 and 22 and with a erforation (not shown) corresponding to t e perforation 19 in the telephone-receiver casing 18.V

In assembling the telephone receivers 1 and 2 within the'main casing 21, the telephone receiver 18` is Afirst, positioned within the main casing 21 ywith the bindin posts 22 and 22 extending, respectively, t rough the perforations 24 and 25 and with the perforation 19 registering with the previously mentioned one (not shown) in the casing 21. A resilient washer 26 Jmay. be interposed between the receiver casing 18 and the main casing 21 to provide a resilient support for the several receiver casings. The diaphragm 3, with one or more spacing members 27, is next positionedover the pole pieces 13 and 14 andthe receiver 1 isv then lnserted in the main casing 21, with the pole.

sor

ses

pieces 4 and 5 thereof also facing the diaphragm 3. The several arts within the casing 21 may be secure in position by means of a threaded clamping member 28 en aglng the casing 9 of the'receiver 1.

he relative position of the two receivers 1 and 2 is such that the north pole, `say 5, of the receiver 1 is directly opposite to the south pole, say 14, of the receiver 2 while the south pole 4 of the receiver 1 is directly opposite to the north pole 13 of the receiver 2. Thus, a magnetic circuit is established which includes the permanent magnet 8, the pole piece 5, and air gap 29 between the pole pieces 5 and 14 including the diaphragm 3, the pole piece 14, the permanent magnet 17 the pole piece 13, and air gap 31, between the pole pieces 13 and 14 also including the diaphra m 3, and the pole piece 4. Since the uni irectional fluxes entering and leaving the portions of the diaphragm 3 disposed in the a1r gaps 29 and 31 are equal, the magnetic forces operating on said diaphragm '3 balance. Moreover, the constantlmagneticflux component passes through the diaphragm 3 transversely to the plane thereof, hence preventing the saturation of the same.

When the several. magnetizing windings are connected inqthe manner illustrated dla-` grammatically in Fig. 4` and when the curp rents are caused to traverse the same in the Y diaphragm direction indicated, the magnetic linx-established by magnetizing windings of the receivers l and'2 is caused to traverse paths indicated by arrows a and b; respectively. The

magnetic circuit of the magnetizable windings of the receiver 1 includes the magnetizable pole pieces 5, a space 32 between the-end of t e pole piece 5 and the diaphragm 3, the

3 a space 33 between the diaphragm 3 and lthe'pole piece 4, the pole piece 4 and the permanent magnet 8, Lall as indicated byarrow a. The ma etic circuit for the exciting windings of t e receiver 2 includes the pole piece 14, a space 34-between the pole piece 14 and the'diaphragm 3, the

diaphragm 3, a space\35 ybetween the diaphragm 3- andl the pole piece 13, and the' permanent magnet 17, all as indicated by,

arrow b. 4

The flux produced by the windings 6 and 7 of the receivery 1 is/in the same direction as the iux of thepermanent magnets in the air-gap spaces 29 and 33, thereby increasing the forces operating to move the diaphra m 3 toward the pole pieces 4 and 5. AThe` ux produced by the magnetizable windings 15l and 16 is in the opposite direction with respect tothe flux of the permanent magnets in the air-gap spaces 34 and 35 and hence decrease the forces operating to move" the dia- ``phragm 3 toward the pole pieces 13 and 14.

The result is an unb :operating on the diaphragm 3, and hence a ancing of the forces movement of the latter. When the direction of the current through the several exciting windings reverses, there is a corresponding change in the direction of the unbalancing of the forces operating on the diaphragm 3, causing motion in an opposite direction. Thus, it is seen that, when vbratory electrical 'energy is supplled to the several magnetizing windings, the diaphragm 3 is v1- brated in accordance with the frequency of such energy to produce-sound waves. l

It is again noted, that the unidirectional flux passes through the diaphra m 3 transversely to the plane thereof, theregby preventing the saturation of the diaphragm 3. Hence, the intensity of the liux established by the -magnetizing windings may be greatly increased over value heretofore considered possible without saturating the diaphragm 3, resulting in'a receiver of greatly increased eliiciency.

The audibility-frequency operating characteristic ofthe device embodying vention, asfcompared with'that ofthe ordinary receiver', is shown by curves c and d,

respectively, in Fig, 6, where the. abscissae represent frequency and the ordinates audibility. By the designating, say 1000 audibility, 1s meant a response of such intensity that the signal current may be reduced 1000-times without rendering the signals inaudible, further reduction however, rendering the lsame inaudible. Referring to curve d`for the'ordinary` receiver, it is noted that the audibility of the receiver increases-from a relatively low value to a maximum value at 1000 cyclesand then decreases with further increase in frequency'. The intensity or audibility of incoming signals for a recelveri having such curve varies greatly'for slight change in frequency, thereby introducing distortion, particularly disturbing in the reception of music. Such undesirable result, howeveigis not present in the operation of my invention, as shown by curve c, since the audibility curve remains substantially iat for all frequencies within the normal audible-frequency range.

I' have found/that improved lresults are i obtained by decreasing the dimensions of the chamber formed by the casing 18- and connected with air by the perforation 19 therein. In the drawing is shown one method for accomplishing this result which consists in filling said chamber with an insulaing material and leaving a small space between its outer surface and the surface of the diaphragm.' A perforation 37 may be pro-l vided 'nthe wax, which is so disposed as to' register with the perforation (not lshown) in the casing 18, thereby connecting the dlaphragm 3 with air.

In the foregoing portions of the specifica.

tion, my invention has been described in the form of a telephone receiverbut, of course,

itis also opera le as a telephone transmitter.

In Fig. 5 is shown a preferred construction for use in transmitter circuits. The structure there vshown comprises a permanent magnet 38 of U-shape 'having a control magiietizable polar projection 39. A second permanent magnet 41 of U-shape, having a similar magnetizable polar projection 42, is positioned in spaced relation with respect to the lirst mentioned permanent magnet in such manner that poles 42, 43 and 44 thereof face opposite poles 39, 45 and 46 of the permanent magnet 38.

The two permanent magnets 38 and 41 form a pair of parallel-connected magnetic circuits, as indicatedL byarrows e and f, having air gaps 45, 46 and 45, 47, therein, re-

spectively. A diaphragm member 48 may be positioned in the air gaps 45,46 and 47 intermediate the several poles. The magnetizable polar proj ectioIisl 39 and 42 may be provided with magnetizing windings 49 and 5l. windings may be connected by al conductor 52, while the outer ends may be connected to a source 53 of direct-current energy by means of a conductor 54 and 55, res ectively. The two paths for the ilux estab ished by the magnetizing winding 49, are indicated by arrows g and i, while the two paths for the flux established by the magnetizing winding 51 are indicated by the arrows k and Z.

^ In operation, when the diaphragm 48 is caused to vibrate, the reluctance of the magnetic circuits of the magnetizing coils is increased in the case of one coil and decreased in the case of the other coil, thereby decreasing and increasing, respectively, the intensity lof the :flux traversing the magnetizing coils.

The effect of such variations in the intensity of the flux is to cause corresponding potential variations across the terminals of said magnetizing coils. Such potential variations may be translated into useful current variations by connecting one conductor 56 of an external circuit 57 to either of the outer ends of the magnetizing coils 49 and y51 and by connecting the other conductor 58' of said circuit to the conductor 52 connecting- .the inner ends of. the coils 49 and' 5l. A conofmy invention in detailand while I have pointed out certain of the most obvious principles, I do not intend that the language employed in the following claims shall be The inner ends of the magnetizingY being oppositely directed with respect to that between the other pair, a diaphragm vibratably positioned in the space intermediate said pole pieces, the forces exerted on said diaphragm by said pole pieces balancing, magnetizing windings magnetically associated with said pole pieces for disturbing the ing enclosing said foregoing elements and formed substantially into two chambers by said diaphragm, and means for'decreasing the inner dimensions of one of saidchambers, said casing having a perforation for connecting said chamber with air.

2. In combination, a sound-wave translating device of the magnetic type having pole pieces carrying.l exciting windings, a second device having corresponding parts, the poles of one device being spaced from the poles of theother device, a magnetizable member vibratably. positioned in the space intermediate said poles, a casing enclosing said elements forming a chamber on each side of said ma n'etizable member, said casing having a per eration connecting one of said chambers with air, and means for defining the dimensions of the o en s ace between said diaphragm and sai per oration.

3. In combination, a sound-wave translating device of the magnetic type having pole pieces and magnetizing windings operatively associated therewith, a second device having substantially corresponding parts, said device bein so arran ed that the poles of one device ace the po es of the other device in spaced relation, a magnetizable diaphragm member vibratably positioned in the space intermediate said poles, a casing enclosing said elements forming a chamber on each side of said diaphragm, and an insulating material disposed within one of said containers and forming a relatively small open space between the exposed surface thereof and said diaphragm, said casing and said insulating material having a perforation connecting said small open space with air.

In testimony whereof, I have hereunto subscribed my name this 27th day of December 1922.

FRANK CONRAD. 

